Not a bad question.

The easiest way would have been leaving Anakin's fate unclear, and Palpatine not giving him a new name. (He has to earn it by killing the Jedi and Separatist leaders first.) Leave him at the lava's edge, and don't show what happens after Palpatine finds him. I think some fanedits have done this.

When Vader appears for the first time in Episode IV, there at least would be some doubt as to whether it's Anakin or some other apprentice. Palpatine seems to go through a lot of them.